1983ApJ. . .264. .594K 1-2 a fewwell-knownplanetariesthatarepartofstudy unusual interest.Alsoincludedarephotometricdatafor data forseveralobjectsandtolooknebulaeof nebulae thatwasconductedtoimprovetheabsolute central starmagnitudes,whichwillbereportedonlater. © 1983.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. The AstrophysicalJournal,264:594-598,1983January15 Temperature shiftsand,wherepossible,radialvelocity (plus HeiiPi8)fluxdeterminedforNGC7027by telescope atPrairieObservatory,asingle-channelpho- and reductionproceduresarediscussedbyKaler(1976, tometer, andasetofinterferencefilters.Observation NGC 7008,wereobservedwithbothrestrictedand were observedwithapertureslargeenoughtoencompass Shaw andKaler(1982)of7.60X10"ergscms". Ä.4959 [Oin],X6563Ha,andX6584[Nn]incolumns diameter ofthephotometerapertureused.Theobserved Kohoutek (1967)number,andcolumn(3)givesthe and (2)givethenebula’scommonnamePerek- shifts weretakenintoaccount. presented forX3727[On],À4471Hei,X4686ii, given infootnote“b.”Twonebulae,NGC6537and one ofthese(A77),baseduponthenebulardiameter,is (5) .Inallbutthree cases(seefootnote“a”),thenebulae uncorrected forinterstellarextinction. TherelativeHa the wholeobject.AnestimateoftotallogF(Hß)for absolute HßandHafluxesaregivenincolumns(4) (6) through(11).Allabsolute andrelativedataaregiven adequately largeapertures. 1980a, 1981).AbsolutefluxesaretiedtothenewHß flux incolumn(10)willnot always beconsistentwith This paperpresentstheresultsofasurveycompact All theobservationsweremadewithIllinois1m The dataarepresentedinTable1,wherecolumns(1) Relative linefluxes,onthescaleF(Hß)=100,are © American Astronomical Society • Provided by theNASA Astrophysics Data System least oneandpossiblymorenebulaewithhighN/O,including(NGC6537)thatappearstobe highly enrichedinbothnitrogenandhelium. high excitationnebulae,examinationofthreeverylowobjects,andthediscoveryat heretofore examined.Mostarecompact,andsomehaveextraordinarilyhighreddeningconstants. Subject headings:nebulae:abundances—planetaryspectrophotometry Principal resultsincluderevisionofsomepreviouslymeasuredHßfluxes,thediscoverytwovery A PHOTOMETRICSURVEYOFCOMPACTANDSELECTEDPLANETARYNEBULAE Absolute andrelativelinefluxesaregivenfor31planetarios,includingseveralthathavenotbeen I. THEOBSERVATIONS Astronomy Department,UniversityofIllinois Received 1982April30;acceptedJuly19 James B.Kaler ABSTRACT 594 by dividingthevaluesofcolumn(11)thosein umn (12)givestheratioofX6584[Nn]fluxtothat ing effectsbetweendifferentnight’sobservations.Col- of Ha,calledN/a.Thisratioisthesameasthatfound that derivedfromcolumns(4)and(5)becauseofweight- (1971) theoreticalvalueof2.85,andtheWhitford(1958) Hß isremoved.Column(13)givestheinterstellarex- column (10),buttheerrorisdifferent,sincein reddening function[/(Ha)=—0.335].Notethenumber derived fromtheHa/Hßfluxratio,Brocklehurst’s in Table2.Thepositionsareforthecentralstarwhereit quence, newcoordinatesweremeasuredforselected offset, usuallyfromanearbySAOstar.Asconse- observed withthissystemarepresentedimproved of heavilyreddenednebulae,onewithc«2.8(Ml-78). tinction constant,thelogarithmicextinctionatHß,c, is seen,orfortheopticalcenterofextendednebula. nebulae fromthePalomarSkySurveyandarepresented however. The errorsassignedtotwooftheobjectsarederived relative linefluxesareingoodagreement.Na-1and recently observedbySabbadin(1980):thetwosetsof table aregivenincolumn(14).Sevennebulaepreviously given; therelativefluxesshouldbereasonablyreliable, Ml-11 wereobservedbyKondratyeva(1978,1979):for and/or moreextensivedata.ThenebulaeM4-18was errors ontheabsolutefluxesareprobablyhigherthan found fromextensiveunpublished measurements,are from offsetstwoSAO stars. Themeanerrors,as earlier. Forthethreenebulaenotedby“poornight,” the presentHa/Hßratioisalmostdoublethatfound the latter,N/aratiosareinexcellentagreement,but ±3". The fainternebulaehadtobeobservedbyblind Notes toremarksandreferencesattheendof 00 00 CM KO O'! LO ft

TABLE 1

© American Astronomical Society • Provided by theNASA Astrophysics Data System Observed Line Fluxes and Extinctions for Compact and Selected Planetary Nebulae Æ o 'O 2- Ä ° 'O Ö cn ■ V-/ ^ r-t Æ r-t z o ^ z ^ 3 ^-v n ó o ON O CM vOno ON .oo CM 00o- CMr-ir-lr-l^ O CMt—!CO00 41 CM r-tor-l CO t—IvOO 41 -B 41 4H -B *41 o <__ -H +1 00 -d-r^.r-4 r-l 00 non 41 P O ■B 41-B 41 41 -B ; m oco r-i •oom i—I vOO ON r-l

aNebula larger than aperture; value given is the surface flux through the aperture in col. (3). bSurface flux; total log F(¥Lß) estimated to be - 12.40 + 0.10. cNo detection. Remarks.—(1) Misses some of outer shell. (2) Central core. (3) Poor night. (4) Inner ring only. (5) Kaler 1980a. (6) Bright blob. (7) Kaler 1978/>. (8) W8, extinction doubtful. (9) Aller, Kaler, and Czyzak 1976. (10) Kondratyeva 1979. (11) Kohoutek 1972 suggests emission-line star. (12) Sabbadin 1980. (13) Kaler 1976. (14) Kondratyeva 1978. 1983ApJ. . .264. .594K 596 by 0.02.Exceptforthreenebulae,theagreementis data arecorrectedtotheOkeandSchild(1970)stan- measurements inTable3.Wherenecessary,theolder NGC 6537,whichisheremeasuredtobe0.40inthelog dard, asdescribedbyShawandKaler(1982).TheAD brighter thanpreviouslybelieved.CDOmeasuredonly reduced by0.04inthelog,CD0.01,andothers and BARdatawereunchanged,theFTPvaluewas night, andtheCDOvalueisalmostcertainlybetter here enclosestheentireouterdiameterofthisextended generally satisfactory.Thelargestdiscrepancyisfor present fluxandthatmeasuredbyBarker(1978),but Within theerrors,thereisnodifferencebetween is probablypreferable. object. NGC6778wasobservedonarelativelypoor the innercoreofobject,whereas4'apertureused nebula, wasobservedinordertotestforvariability. excellent night,togetherwithothernebulaethatconfirm of thetwo.NGC6790,however,wasobservedonan interest becausetheyareatthe extremesoftherange reference, theobservationwasmade1981January23 observed ionization.Ha3-29 andK3-63bothexhibit UT. the objectshouldbeexaminedperiodically.Forfuture the validityoffluxmeasurement,andnewvalue strong HeilX4686.Helium appears tobefullydoubly The newtotalH/3fluxesarecomparedwithprevious Ml-2 (W8),awell-knownpeculiarhighdensity Several ofthenebulaeinTable 1areofparticular © American Astronomical Society • Provided by theNASA Astrophysics Data System Ha3-29 All... Vy2-3.. Ml-2 . K3-63. K3-60. Ml-7 . Ml-4 . Ml-13 Ml-11 Me2-1 M4-18 M2-54 M2-2 .. Ml-79 Ml-78 Nebula b) HighandLowExcitationNebulae Coordinates forSelectedNebulae hms 21306?2±. 07 1902.6 07 0905.9 04 3421.5 06 3417.8 04 0910.2 03 3759.0 23 2036.0 22 4930.9 01 5532.5 21 3734.5 21 2558.1+0.1 04 2130.8 21 1905.7 15 1923.5 21 3511.7 a) AbsoluteFluxes II. DISCUSSION TABLE 2 (1950) , + 523910 + 553227 + 245650 + 55°3927"±V + 240307 + 520726 + 5726054 + 463729 + 600018 - 180250 -19 4601 -23 2652 + 513446 + 564916 + 514038 + 484241 KALER -1 - ! + - ] ionized intheformer,anditisthatsensecomparable is probablyalowerlimittothetrueeffectivetempera- nitudes ofÆ=18.8,V18.6,theHenZanstratempera- If weadoptShaoandTiller’s(1973)centralstarmag- (Sabbadin 1980),Ml-11(Kondratyeva1978),andM2-54 not welldefined. (Kohoutek 1972).Thepresentdataconfirmthe ture becausethenebulaislikelytobeopticallythinin to thehighexcitationnebulaestudiedbyKaler(1981). discussed above,andMl-13,116kms,alsoappears of +92kms,isonetheverylowexcitationobjects (see PerekandKohoutek1967)areconsistentwith K. Allareverysmallandunresolved,consistentwith From Kaler(1978¿z),thecentralstartemperaturesof of [Nii],however,indicatesalowexcitationplanetary. emission linestar,basedonthestrengthofcon- Kohoutek (1972)suggestedthatM2-54mightbean [O m]intensitiesfoundearlierforM4-18andMl-11. the HeLymancontinuum. ture (HarmanandSeaton1966)is113,000K.Thisvalue their beingyoungplanetaries. the threeobjectsareallinneighborhoodof30,000 tinuum, andalackofblueemissionlines.Thestrength to beoflowexcitation,althoughtheX4686strengthis are confinedtothedisk.TheTSRradialvelocityofHa Kaler’s (1980/?)contentionthathighexcitationnebulae 3-29 islow,at-36kms.Ml-11,withahighvelocity NGC 6572 NGC 6537 NGC 6543 NGC 6879 NGC 6790 NGC 6778 J 900. NGC 7008 IC 2149.... Ml-2 . Capriotti andDaub1960.CDO: Collins, Daub,andO’Dell Me2-1 1961. Lili:Liller1955.OD62:O’Dell 1962.OD63:O’Dell 1963. P71:Perek1971. Three nebulaeexhibitveryweak[Om]Unes:M4-18 The nebulaeforwhichradialvelocitiesareavailable a Nebula References.—AD: Adams1975. BAR: Barker1978.CD: Excludesouterpartofshell. Comparison ofHßFluxes 11.40 +0.03 11.34 +0.02 10.55 +0.01 11.57 +0.01 10.86 +0.01 11.18 +0.04 11.31+0.01 11.88 +0.06 10.84 +0.03 9.83+0.01 9.59 +0.03 New — logF(Hß) TABLE 3 a 11.80 10.51 Other 11.37 11.30 10.88 11.62 10.77 11.28 11.32 11.99 11.92 10.55 9.87 9.80 9.78 9.63 Reference Vol. 264 CDO AD CD CD CD OD 63 BAR CD Lili CDO CDO OD 62 CDO P71 FTP P71 1983ApJ. . .264. .594K No. 2,1983 known. Inparticular,theionicabundancesarequite Nevertheless, wecanusethedatatosurveynebulae greater detail.ThissurveyispresentedinTable4. sensitive tothefrequentlyunknownbuthighdensities. these databecausethenebularconditionsarenotwell to lookforobjectsofinterestthatcanthenbestudiedin is used.Theletter“s”meansthatthenebulaappears in pc.Thesearegivenundertheassumptionsofeither nebulae insecondsofarcfromPerekandKohoutek used byCahnandKaler(1971), andthe“thick”dis- constant massorluminosity,whicheveryields (1967). Whenanebulaexhibitstwoshells,theinnerone nebulae determinedbyCudworth (1974).Thelatter suggestion. Theconstant-massapproachisappropriate and (4)thenpresentthedistances(D)radii(R) Column (2)ofTable4givestheangularradii(<¡>) electron densitiesfromthephysicalradiiofnebulae. thick. The“opticallythin”distances arefromthesystem to theopticallythinnebulae,other stellar andthathasnotbeenmeasured.Columns(3) tances employthemeanabsolute magnitudeofthe the lesserdistance,inaccordwithMinkowski’s(1964) An accurateabundanceanalysisisnotpossiblefrom The firststepistomakethebestpossibleestimatesof © American Astronomical Society • Provided by theNASA Astrophysics Data System communication, AllerandEpps1975,Aller,Kaler,Czyzak1976,Minkowski1942,forNGC6881unpublishedKitt NGC 6537 Kaler 1971.Othersbasedonusualconstantmassassumption. Peak 1RSdata. A 77 NGC 7008 NGC 6881 NGC 6879 NGC 6790 Ml 4. Ml 13 Ml 7. K3 63 Ha3 29 N/O mayreflectunderestimateofT.(5)estimatedfromPalomarSkySurvey.(6)HighN Ml 79 Ml 11 If T=10,000K,N/Odropsto0.31.(3)HighvalueadoptedforNis¿ghexcitationblob,appropriate40"data.(4)Low M4 18 M2 54 e e b a Distance basedonassumptionofconstantluminosityandCudworth’s1974absolutenebularmagnitude,scaledtoCahn T and/orNadoptedfrommeasurementsoneormoreofthefollowingsources:AllerandCzyzakprivate Notes.—(1) Tfromobservationsofcentralcore;meanvaluefor40"apertureprobablybetweenthetwovaluesadopted.(2) e e Nebula (1) <5 <5 c) Abundances 21 16.5 (2) 4.5 2.0 4.4 7: 3.9 3.6 5.0 1.6 b b b b b b 4300 2100 2200 3000 4600 2100 5500 8500 1300 1300 1700 (pc) 780 (3) D R <0.15 SURVEY OFPLANETARYNEBULAE (pc) (4) 0.03 0.13 0.02 0.02 0.15 0.17 0.05 0.12 0.17 > 60 Survey ofNebularProperties (K) 3 10" 20 11 (5) 0.6 0.6 0.9 0.4 0.4 3.5 8.6 1.0 Adopted T a e TABLE 4 10 1.6 1.0 1.0 1.0 1.5 1.0 1.1 1.5 1.0 1.2 1.0 1.0 1.0 1.0 1.0 1.0 (6) -4 43 estimate thermsdensitiesofthicknebulae.Columns(6) are thencalculatedfromtheadoptedmassof0.18M footnote “a.”Thermselectrondensitiesincolumn(5) distances arescaledtotheformerandindicatedby N/O derivedfromtheobservationsandprocedures or fromcolumn(5).TheTareusuallysetequalto measurements byothers(seethereferencesinTable4), and afillingfactorof0.65.Thisprocedurewillover- (and atomicconstants)givenbyKaler(19786,1979, and (7)thenlisttheadoptedTN,eitherfrom adopted becauseofthehighexcitation. in heliumandnitrogen.He/Happearstobeatleast is NGC6537,whichappearstobeveryhighlyenriched unreliable (seeKaler1979).Themostinterestingobject excitation nebulae,forwhichtheratioisparticularly N/O andHe/Hdefinedby Kaler (1979).Itisdifficult The objectfitswellattheendofcorrelationbetween 0.14, andN/Ooforderunitythenebulaclearly qualifies asanotherexampleofPeimbert’s(1978)typeI. 3 are probablytheleastfavorable circumstances(T= to drivetheN/Oratiodown by verymuch.Underwhat 9700 K,N=10cm"),N/O stillequals0.53. 10,000 K,exceptforHa3-29,which15,000Kwas 0 1980 a).TheN/Oarenotpresentedfortheverylow e e a a (1) N e e e a a 10“ 20 20 60 10 10 10 4 4 4.0 Columns (8),(9),and(10)presentHe/H,O/H, 1.0 1.0 1.0 1.0 1.0 >0.10 0.24 +0.10 0.13 +0.01 0.13 +0.02 0.18 +0.04 He/H O/H (8) (9) 4 IO“ 6.2 4.3 2.6 2.9 0.9 4.2 7.7 3.2 5.7 1.6 1.2 >0.11 0.04 0.56 0.16 0.08 0.68 0.45 N/O Notes 1.0 1.8 1.4+1.0 (10) (11) 597 1983ApJ. . .264. .594K + -1 598 pear toshowelevatedHe/Hratios.ForNGC6790, Aller andCzyzak(1979)measureamorereliablevalue of 0.10fromthreeHeilines,implyingthatthe/FI .1978a,Ap.J.,220,887. Aller, L.H.,andCzyzak,S.J.1979,Ap.SpaceSei.,62,397. Adams, T.F.1975,Ap.202,114. ingly. Ifso,He/HforNGC7008andMl-79iswithin ratios fortheothernebulaemightbereducedaccord- .1980a,Ap.J.,239,78. .1978/?,Ap.J.,226,947. Barker, T.1978,Ap./.,219,914. Aller, L.H.,Kaler,J.B.,andCzyzak,S.1976,Ap.J.,203,636. Aller, L.H.,andEpps,H.W.1975,Ap.J.,197,175. .1981,Ap.J.{Letters),250,L31. _.1980/?,Ap.J.,237,491. .1979,Ap.J.,228,163. Kaler, J.B.1976,Ap.J.,210,113. Cudworth, K.M.1974,A.J.,79,1384. Collins, G.W.,Daub,C.T,andO’Dell,R.1961,Ap.J.,133, Capriotti, E.R.,andDaub,C.T.1960,Ap.J.,132,677. Cahn, J.H.,andKaler,B.1971,Ap.Suppt.,22,319. Brocklehurst, M.\91\,M.N.R.A.S.,153,471. Harman, R.J.,-andSeaton,M.J.1966,M.N.R.A.S.,132,15. the errorof0.10,butthatforNGC6537isstillhigh, study. SomeoftheothernebulaeshowelevatedN/O, Kohoutek, L.1972,Astr.T/?.,16,291. [O ii]line.Itmaybearewardingobjectforfurther so tooistheerror,becauseofbarelydetectedX3727 James B.Kafer:AstronomyDepartment,Universityof Illinois,341AstronomyBuilding,1011W.Springfield, values. Thevariationmayreflectuncertaintiesinthe and stillsomeotherobjectsappeartohavequitelow Urbana, IL61801 conditions andpossiblesystematicerrorsinX3727 logF(Hß) =-12.70+0.03;logF(Ha)11.760.08;/(X3727)68+15;/(X4686)6526;/(X4959)43337; unknown. ForT—10,000Kandlowdensity,N/O«1,whichsuggeststhatBV-1maybeanotherPeimberttype I counter totheresultsofKaler(19806):see§116.However,erroron/(X4686)ishigh,andv is /(X6563) =835±182;/(X6584)995+126[where/(X)100F(X)/F(Hi8)];N/a1.19+0.27;c1.40±0.25.The nebula. Theobjectmeritsexaminationingreaterdetail. excitation ishighforitsradialvelocityof-94kms,whichyieldst;=-89marginally >0.12. e r LSR 471. NGC 6790,7008,andparticularlyMl-79ap- The N/OratioforNGC7008isnominallyhigh,but Note addedinproof.—ObservationsofBV-1=PK119+0°1wereinadvertentlyomittedfromTable1.Thedataare © American Astronomical Society • Provided by theNASA Astrophysics Data System REFERENCES KALER photometer, andR.ShawK.Huffordwhomade esting objects.Particularnebulaethatshouldbe examined inmoredetailaretheveryhighexcitationHa earlier result. M4-18 isoxygendeficient,confirmingSabbadin’s(1980) [O ii].TheO/Hratiosfallwithinthenormalrange. and probablyNGC7008. and M2-54,thenewPeimberttypeInebulaNGC6537, 3-29 andK3-63,theverylowexcitationnebulaeMl-11 some oftheobservations. thank E.C.Olsonforthehighperformancelevelof 80-23233 totheUniversityofIllinois.Iwouldlike .\964,Pub.A.S.P.,76,197. .1979,Astr.Zh.,56,345. .1963,Ap.J.,138,293. Perek, L.,andKohoutek,L.1967,CatalogofGalacticPlanetary Perek, L.1971,Bull.Astr.Inst.Czechoslovakia22,103. Peimbert, M.,andTorres-Peimbert,S.1971,Bol.Obs.Tonantzintla Oke, J.B.,andSchild,R.E.1970,Ap.J.,161,1015. Minkowski, R.1942,Ap.J.,95,243. Filler, W.1955,Ap.J.,122,240. Kondratyeva, L.N.\91%,Astr.Zh.,55,334. Whitford, A.E.1958,A.J.,63,201. Peimbert, M.1978,inIAUSymposium76,PlanetaryNebulae,ed. O’Dell, C.R.1962,Ap.J.,135,371. Shao, C.-Y.,andFiller,W.1973,privatecommunication. Sabbadin, F.1980,Astr.Ap.,84,216. Shaw, R.A.,andKaler,J.B.1982,Ap.J.,m.press. y Tacubaya,6,21. Y. Terzian(Dordrecht:Reidel),p.215. Nebulae (Prague:CzechoslovakAcademyofScience). This researchwassupportedbyNSFgrantNo.AST In summary,thissurveyuncoversanumberofinter-